In tossing four fair dice, what is the probability of tossing, at most one 3?
This is the beginning of the solution I have:
The number of outcomes of tossing four dice is $6 \times 6 \times 6 \times 6 =6^4$.
Outcomes of getting at most one 3 = outcomes of getting no 3 $ +$ outcomes of getting one 3.
The number of outcomes of getting no 3 is $5 \times 5 \times 5 \times 5 =5^4$.
The number of outcomes of getting one 3 is $4 \times 5^3$.
But I don't understand why it's $4\times 5^3$. Can any one assist?